Treatment of cotton goods



UNITED STATE TREATMENT OF COTTON GOODS William Beach Pratt, Wellesley, Mass, assignor 3 Elaims. (Cl. 8-2) ,l,/ The subject of this invention is the treatment fural, for example, appears to exhibit the prop- 7 w" of unbleached cotton goods with a view toward erty of being selectively absorbed by the cotton luster therein, while preserving strength, age retion of a liquor containing an oxidizing bleach, 5 sistance, and other important physical characit is possible to 'realize'goods of excellent whiteteristics. In speaking of cotton goods, I mean ness, cleanliness, softness, strength, absorbency.

" not only piece goods or fabrics, but also yarns and other desirable physical characteristics.

such as are intended to enter into fabric-making. Not only do the shives and motes quickly disap- 1 In preparing unbleached cotton goods for the pear from the goods in the bleach liquor, but 10 market y g ,Ot e fi sh ng operastarches and other sizing agents are so comtions, it is customary practice to remove colorpletely destroyed that tests show no vestige ing matter and other impurities, including shives thereof. It is apparently the case that the aldeand motes, therefrom. Piece goods usually 0on hydeassociated with the goods is transformed by toin sizing a ts, such as starch and/or glue, in oxidation in situ in the goods into an organic 15 addition to e Original u s a d Wa es natural y acid,,which not only assists the bleaching action,

Occurring in the ot fibe which u t be but does so .without physical or chemical degeliminated in order to realize the desired softness radation of the cotton fiber. Then, too, the reand other optimum characteristics in the finished action on the aldehyde taking place quickly in goods. It has been generally the practice to boil situ in the goods evidently tends to throw off 20 V cotton goods in caustic soda solutions and then mechanically from the fibers or yarns the shives,

t0 bleach the Washed goods before dyeing a d/0 motes, sizing or other contaminative matter car- 'mal'ketihg them- The bo ng t ea ent in ried superficially thereon. In the case of starch caustic soda solutions must in many cases be sizing, it may be that the acid condition deperformed for a l p ri d f t m n t nly veloped tends to hydrolyze and dissolve the 25 cause it s d fii t t wet cotto oods t o g y. starch. Whatever may be the chemical and/or but because Seine p es. Such as a ch S physical explanation for the results which I ses, are r i ant to rem val even by prol n d cure, it is a fact that by practicing the steps boiling- The W s, u res naturally hereinbefore described, it is possible to secure 3o Occurring in Cotton fiber a ous y interfere these results consistently and with various kinds With the wetting of raw Cotton goods, s attested of cotton goods in a period of time which is but y th fa t t at aw. unsiz d tt n skeins or a fraction of that required by the usual treat Piece ds. w n put into water r austi s da ment with caustic followed by bleaching. l: have Solutions, Will float for a Considerable period Of observed that goods processed as hereinbefore time before y imbibe Sufficient Water o eXerdescribed invariably reach a distinctly acid con- 35 e s a t nd y t k- Th se ndit s pr dition at the end of the bleaching operation, vail esp ia y ineommereial s a p at i despite the fact that the bleach liquor em lo ed, v lvin he boiling treatment of thousands of or the goods themselves, may be distinctly alka.

, p unds of cotton goods as a single bat h n a line at the beginning of the bleaching operation.

40 kier wherein there is -o p ity fo a i- This acid condition is attributable to the oxidaso tation of the caustic soda solution and/or the t n of the aldehyde to organic acid in situ in goods. the goods, as hereinbefore described.

I ave discovered that n preparing cotton The principles of my invention may be applied goods of the character described, for subsequent. in various and through the use of various b1eaching, more especially-with liquors containaldehydes, t I prefer to ork with formalde- 45 ing oxidizing bleaching agents u a Sodium l hyde as my aldehydic agent, primarily because a hydrogen Peroxide, calcium yp i of its low cost as compared with other commercial ehlelihe,v the ke, it is distinctly advantageous aldehydes, such as furfural. Unfortunately, howjec t e ds to t e act of aqueous i ever, formaldehyde is an acrid gas and, when used 3. ns of 31dehyde Aside from the fact that in aqueous solution (formalin), is expelled from 50 Such Solutions P055655 the a y to W the y 3 the solution rapidly under only moderate heating.

' ;goods quickly throughout, especially at elevated Again, formaldehyde is not selectively absorbed ternperatures, some of them appear to be selecby cotton and being miscible with water leaches tively afiiorbedby the cotton fiber so that they from the cotton when the latter" is placed in a bleach solution. I have discovered, however, that 55 to John Abbott, Everett D. Chadwick, and.

Marcus B. May, trustees, all

Mass.

of Winchester,

No Dra. Application July 15, 1932,

Serial No. 622,831

developing such desirable characteristics as cleanliness, softness, absorbency, whiteness and cannot be removed by ordinary washing. Furfiber from aqueous solution. When the goods, wet with aldehyde, are then subjected to the acit is possible to work in a highly practical and satisfactory way with aqueous formaldehyde solutions if they are properly treated with alkalies such as caustic soda or caustic potash. Thus, I have found that by mixing caustic soda or caustic potash and formaldehyde in substantially molecular proportions, together with water in amount to yield an aqueous solution of the desired strength in alkali, and then boiling the mixture, the formaldehyde is quickly converted into a nonvolatile reaction product of a dark brown color, which not only behaves like an aldehyde on cotton goods, but is selectively absorbed by the cotton. In commercial practice, it is preferable to use solutions of alkali of about 2% strength, in which case the liquor containing the reaction product may be prepared by using 2 parts by Weight of caustic soda to 5 parts by volume of the 40% com= mercial formaldehyde (formalin) and 100 parts by weight of water. I prefer to use formaldehyde in amount somewhat in excess of the mol. equivalent of the alkali, as this ensures the desired reaction product. It is only for purposes of economy in the aldehyde that it is undesirable and, in fact, unnecessary to use much. excess of aldehyde, although the desired reaction seems to go more nearly to completion when as high as two mols of aldehyde are used to one mol. of alkali. On the other hand, I have been unable to realize the desired reaction by having the alkali present in mol. proportion in excess of the formaldehyde. It is quite likely that the caustic soda, under the conditions described, serves to catalyze a condensation or polymerization of the formaldehyde into one or more aldehydes of much higher boiling point, but the condensation reaction seems to go to a definite end point at which the condensation product issoluble in water and imparts a definite depth of coloration thereto. In other words, prolonged heating of the solution evidently does not conduce to further reaction; and, if the water is evaporated from the solution, it is possible to re-- place the evaporated water so as to restore the solution to its original dilution. It may be that, in view of the necessity for using mol. equivalents of alkali and formaldehyde, the alkali enters into chemical combination with the formaldehyde, but

' even if this is the case, the reaction product displays the reacting tendencies of formaldehyde and upon oxidation tends to go to formic acid.

After having produced my dark brown solution containing what may, for convenience, be termed formaldehyde condensation product, I immerse cotton goods in the solution and heat them until they have been thoroughly wetted with the solution throughout. A boiling temperature under atmospheric pressure apparently is suificient for this purpose.

can be recovered and reused in the treatment of other cotton goods. The goods wetted with the solution are then put into a suitable oxidizing bleach liquor, such as heretofore used, e. g., containing sodium and/or hydrogen peroxides, calcium hypochlorite, chlorine, or the like. The bleaching operation may be conducted under any suitable conditions of temperature and bleach liquor concentration for a period of time consonant with the attainment of the desired whiteness and The treated goods may then be drained or squeezed free of excess solution, which ing, even though they are alkaline as introduced into the bleach liquor, which itself may be initially alkaline. This acid condition is not, however, detrimental to, but, as already stated, enhances characteristics desired in the goods, probably by virtue of the fact that the formic or other organic acid into which the formaldehyde condensation product is oxidized does little, if any, chemical damage to the cotton fiber while increasing its luster or brilliancy, and is substantially completely removed by'the washing performed after bleaching.

It is possible to-practise my invention by adding the cotton goods to a formaldehyde solution before it has undergone the desired reaction, and then to add alkali in appropriate amount and heat the solution so as to bring out the reaction in the presence of the cotton goods. Or the steps may be reversed, with the cotton goods being introduced first into the caustic soda solution, the aldehyde then being added, and heat applied so as to cause the desired reaction.

There are other possible Ways of reducing the volatility of formaldehyde solutions so that they can be used more expedientlyin treating cotton goods. Thus, the addition of soap or other waterreaction in the presence of alkali, as hereinhefore described.'

While I have mentioned more particularly the availability of formaldehyde, nevertheless one may utilize the higher aldehydes, such for example as acet-aldehydes, furfural or butyl aldehyde in the preliminary solution employed before the oxidizing bleach. When an organic acid, such as formic acid, in solution is used as the preliminary treating bath in large scale operations, there is such constant danger of tendering the cotton goods that it does not readily lend itself to factory application. But, on the other hand, when such conditions are realized that the cotton after treatment with an aldehyde solution, retains sufficient of the aldehyde for con version to the acid, there is practically no danger of tendering the goods regardless of the time element of the treatment either in the first or second steps of the process.

In practising the present invention on a commercial scale, it has been established that the time required for the treatment of cotton goods preliminary to the bleaching operation is only a fraction of that required by a treatment carried out in a comparable way with plain caustic soda solution. That is to say, with a given commercial equipment, for instance a kier designed to hold a number of thousands of pounds of cotton goods and liquor and to be run under particular temperature conditions, circulation of liquor, etc., it is possible to shorten considerably the time period through the use of the preliminary treating liquor of the present invention, and yet to realize a notable improvement in the goods. The present invention thus makes possible not only goods of improved quality, but a reduction in operating costs by virtue of the fact that the capacity of a given equipment is increased. The ratio of liquor to cotton goods is, of course, subject to considerable variation, depending upon the nature of the goods and the kind of equipment employed. In any event, however it is desirable that sufficient liquor be employed to cover or completely submerse the goods so that they 0. ULLHLIIHWU uL UIEINU; PLUM TREATMENT, & CHEMICAL MODIF GATIQN OF TEXTILE items,

1m] undergo substantially uniform treatment throughout.

The cotton goods processed in accordance with" 'such aswaxes, gums, s'hives and motes, inherent in raw cotton.

What I claim is:

- 1. A method which comprises polymerizing formaldehyde in aqueous solution into a nonvolatile, water-soluble reactionproduct exhibiting an aldehydic reaction, wetting cotton. goods 20 with the resulting solution, and then subjecting Cross Reference -tion to the action of oxidizing bleach liquor.

nhs

bleach liquor. r

2. A method which comprises treating an aqueous solution of formaldehyde with alkali under conditions to transform the formaldehyde into a non-.volatile, water-soluble, colored reaction product, wetting cotton goods with the resulting solution in heated condition, and then subjecting the goods wetted with the solution to the action of an oxidizing bleach liquor.

.3. A method which comprises heating a mixed solution of formaldehyde and alkali containingsubstantially mol. proportions of both these agents and; of about 2% alkali concentration to convert the formaldehyde into a non-volatile, water-soluble, colored reaction product-wetting cotton goods QEKHUII IlUUIlI the goods so wetted to the. action Ofbxidjzting v with the resulting solution in heated condition,

and subjecting the goods wetted with the solu- I wnLmM BEACH PRATT. 

